Project Summary/Abstract Significance: Opioids kill 250 persons daily in the US, mostly by respiratory arrest. Hypoxemia (low blood oxygen), typically precedes respiratory arrest. Timely detection and correction of hypoxemia saves lives. The Oxalert EPO is a wearable device designed to automatically restore breathing and reverse hypoxemia without human intervention. The Oxalert EPO (Enhanced Pulse Oximeter) is an FDA designated Breakthrough Device, (...more effective diagnosis or treatment for a life-threatening condition... for which no equivalent alternatives exist... in the best interests of patients.)24 The FDA recognizes our initial proposed Indication for Use in hospitalized post- operative patients receiving opioids. We intend to confirm feasibility both in-hospital and at home, in order to support a later FDA Indication for Use in patients at home using opioids. The Center for Medicare and Medicare Services (CMS) will now reimburse automatically for FDA-approved Breakthrough Devices. Preliminary Data: Zornow showed that automatic arousal was superior to 1:1 nursing care.17 Sessler incidentally verified the Arousal Effect in a study of 1200 post-op in-patients.16 Specific Aims: AIM1) Prove feasibility of the Oxalert arousal device for restoring breathing and reversing hypoxemia in post-operative patients receiving opioids. AIM2) Determine statistical scalability needs for future Phase II study. AIM3) Evaluate patient tolerance, nurse feedbacl and human factors/usability. AIM4) Compare the extent of nocturnal oxygen desatuations in home-use before and after surgery, with and without Oxalert interventions. Summary: Breakthrough Device status should facilitate FDA approval for the Oxalert EPO. Devices with a favorable Risk:Benefit ratio under the Twenty-First Cures Act qualify for less FDA emphasis on lengthy pre-market studies as opposed to post-market data in order to expedite patient access. We hope to find the shortest path to getting this device to all who might benefit.